Donald Lee - Him being cut would be a pure salaray dump, and the Packers have paid a premium for depth in the past. He's currently due to make $2 million this season, which is not THAT excessive in base salary. Nothing I've seen out of Havner or Quarless makes me feel Lee is expendable at least from a talent standpoint. Havner is probably the oddman out here. He was a nice story making the roster last year, but with his off the field issues (albeit minor), his developmental third TE spot is probably going to go to the Quarless this year.
Poppinga - Zombo, Obiozer, etc. are going to have to show a lot at OLB for him to get cut imo. He's a good special teams player and locker room veteran even if he's been rather mediocre as a pass rusher. Popps is scheduled to make $2.25 million total this season. A bit of money for a reserve, but again, nothing to excessive like Lee.
Bush - He's like a convenient store pocket knife that is being sold for a quality one. He can do a lot of things on paper, but not any one thing particularly well. If he sees the field again as anything more than a special teams gunner, the secondary is going to be in trouble if they face elite QBs like last year. I personally hope the Packers finally do part ways with him by the end of camp. I'd rather give guys like Bell and Martin more reps.
Barbre - We carried 9 offensive linemen into the regular season after training camp last year and that did not include Tauscher who was not on the team at the time. Taucher, Clifton, Sitton, Bulaga, and Wells are probably locks to make the team. Colledge, Spitz, and Lang are definitely in the "likely to make it" category. That leaves guys like Newhouse, Barbre, Giacomini, Dietrich-Smith, etc. all squarely on the roster bubble fighting for one or maybe two spots on the final roster. Barbre is probably the most likely to be on the outside looking in at the end of camp.
3 FBs - Quite a conundrum. Ideally I think you'd like to trade either Hall or Kuhn for a late round draft pick and keep Quinn and the other non-traded FB if Quinn can show more during camp this year. Quinn would be eligible for the practice squad this year, but frankly, I'd be surprised if he lasted the entire year there even if he made it through waivers at all during the final cutdown. Hall is entering the final year of his rookie deal. Kuhn is entering year 5 and was a RFA this off-season. I'd say keep Johnson for one more year, keep Kuhn, and trade Hall if you can find a willing partner. Hall has been the most injury prone of the trio, and his skills are basically interchangeable with Kuhn's nowadays.